Knives, blades and cutting edge tools have traditionally been made of an essentially uniform material which is typically hardened for cutting purposes. The hardening usually occurs through known heat tempering. Historically, blacksmiths forged axes by folding softer iron around an iron mold and hammer welding a steel insert between the two iron sides so the steel formed the actual cutting edge. This gave a superior cutting edge and conserved the most expensive steel.
Other blades such as samurai blades use methods of incorporating a soft and hard alloy to gain the benefits of both. An example of a knife blade construction utilizing an outer layer of a soft material and an inner layer of a hard material is found in U.S. Pat. No. 3,681,846. In this patent an outer layer of steel or aluminum encases an inner layer of a relatively hard material such as tungsten carbide. Another patent disclosing a laminated knife blade is shown in U.S. Pat. No. 5,256,496. In this patent a titanium-high carbon steel laminate is made with an outer layer of titanium encasing an inner steel blade.
One of the major problems with laminating hard alloy metals is securing the metals together. Delamination of the metals at the interface between the dissimilar metals often results when the laminated cutting tool is put to use. This delamination results in an inferior product and could also result in a safety hazard.
There is a need for a cutting tool which successfully employs a composite structure in the form of a Metal Matrix Composite (MMC), that is light weight. There is a need for a cutting tool which does not delaminate. There is a need for a cutting tool which sharpens itself constantly via the processes of normal use and wear. There is a need for a cutting tool that can utilize a reduced volume cutting edge to save in material cost, the cutting edge being secured within the composite structure via infiltration bonding. Finally, there is a need for a composite knife having a one piece structure that integrally bonds the cutting edge within the structure, and multiple material layers to one another.